def delnum(char):
    b = ""
    for i in char:
        if i.isalpha():
            b += i
    return b


def rollback(char):
    b = ""
    for i in char:
        b = i + b
    return b


def encrypt(char):
    b = ""
    for i in char:
        c = ord(i) + 2
        if c > 122:
            i = chr(c - 52)
        else:
            i = chr(c)
        b += i
    return b


def long(char):
    while char.isspace():
        char = input("Enter:")
        if len(char) >= 255 or len(char) == 0:
            char = " "
            print("重新输入：")
    return char

def main():
    a = " "
    a=long(a)
    a=delnum(a)
    a=rollback(a)
    a=encrypt(a)
    print(a)



main()
